clap

Etymology 1

From Middle English clappen, from Old English clæppan, from Proto-Germanic *klappōną. Cognate with Dutch klappen, Icelandic klappa, and Faroese klappa.

noun

1. The act of striking the palms of the hands, or any two surfaces, together.
   He summoned the waiter with a clap.
2. The explosive sound of thunder.
3. Any loud, sudden, explosive sound made by striking hard surfaces together, or resembling such a sound.
   Off in the distance, he heard the clap of thunder.
   Give the door such a clap, as you go out, as will shake the whole room.
4. A slap with the hand, usually in a jovial manner.
   His father's affection never went further than a handshake or a clap on the shoulder.
5. A single, sudden act or motion; a stroke; a blow.
6. (falconry) The nether part of the beak of a hawk.
7. (Yorkshire) A dropping of cow dung (presumably from the sound made as it hits the ground)
   Oh! get some coo clap (cow dung), mix it wi’ fish oil (whale oil), put it on, and let it stop on all neet. 1890, John Nicholson, Folk Lore of East Yorkshire, page 139

verb

1. To strike the palms of the hands together, creating a sharp sound.
   The children began to clap in time with the music.
2. To applaud.
   The audience loudly clapped the actress, who responded with a deep curtsey.
   It isn’t the singers they are clapping; it's the composer.
3. To slap with the hand in a jovial manner.
   He would often clap his teammates on the back for encouragement.
4. To bring two surfaces together forcefully, creating a sharp sound.
   He clapped the empty glass down on the table.
   She clapped the book shut.
   He clapped across the floor in his boots.
   Then like a bird it sits and sings, / Then whets and claps its silver wings. 1681, Andrew Marvell, The Garden
   1. (slang) To have sex.
      clap alien cheeks
5. (obsolete) To slam (a door or window); formerly often construed with to.
   Her fear gave her strength; she threw Laura away, and clapped to the door. 1792, Thomas Holcroft, Anna St. Ives, vol. VII, letter 119
6. To create or assemble (something) hastily (usually followed by up or together).
   We should clap together a shelter before nightfall.
   The rival factions clapped up a truce.
7. To set or put, usually in haste.
   The sheriff clapped him in jail.
   She was the prettiest thing I'd ever clapped eyes on.
8. (slang, African-American Vernacular) To shoot (somebody) with a gun.
9. (slang) To fornicate, copulate.

Etymology 2

Uncertain. Probably from Old French clapoir (“bubo, inflammation from infection”), from clapier (“brothel”). May also be from old, unsafe treatments for gonnorhea, such as clapping the penis between a book and a hard surface to break up obstructions in the urethra and permit urination. Attested from the 16th century.

noun

1. (slang, usually with "the") Gonorrhea.
   With the mischiefe of the melt and maw, / The clape and the canker, 1821 [c. 1580], Alexander Montgomerie, “The Flyting”, in The Poems of Alexander Montgomery, page 115
   “What in hell makes you think he's got the clap?” Hawkeye asked. “Even a clap doctor can't diagnose it through a parka 1972, Richard Hooker, MASH, page 32
   He thought I had given him the clap [gonorrhea], but I knew I didn't. 1980, Ruth Bell, Changing Bodies, Changing Lives, page 295
   When I explained that I thought he had given me the clap, he said I must be mistaken, it had to be someone I'd “tricked” with at ... He'd never had an STD in his life, he told me, and slammed down the phone. 1998, Dan Savage, Savage Love, page 229
   Gonorrhea, sometimes called the clap, is caused by a bacterium called Neisseria gonorrhoeae.] [2006, Alvin Silverstein, Virginia Silverstein, Laura Silverstein Nunn, The STDs Update, page 40